s 

533 



U. S. DEPARTMENT OF AGRICULTURE. 
BUREAU OF PLANT INDUSTRY— BULLETIN NO. 211. 

B. T. GALLOWAY, Chief of Bureau. 



BACTERIOLOGICAL STUDIES OF THE SOILS OF 

THE TRUCKEE-CARSON IRRIGATION 

PROJECT. 



KART. P. KELLERMAN, 
Physiologist in Charge of Soil-Bucterlology and Wutcr-Purlficalion Investigations, 

AND 

E. R. ALLEN, 
Scientific Assistant. 



IssuEu April 15, 1911. 







WASHINGTON: . 

GOVERNMENT PRINTING OFFICE. 

1911. 




Qass. 
Book. 



S 533 



.K5 



U. S. DEPARTMENT OF AGRICULTURE. 

BUREAU OF PLANT INDUSTRY— BULLETIN NO. 211. 

B. T. GALLOWAY, Chief of Bureau. 



BACTERIOLOGICAL STUDIES OF THE SOILS OF 
THE TRUCK EE-CARSON IRRIGATION 

PROJECT. Ji9 

792 



KARL f[ KELLERMAN, 

Physiologist in Charge of Soil-Bacteriology and Water-Purijication Investigations, 

AND 

E. R. ALLEN, 

Sdentijic Assistant. 



Issued April L5, I'JIL 




WASHINGTON: 

GOVERNMENT l'KINTIN(i OFFICE. 
1911. 



G 



Ti 






BUREAU OP PLANT INDUSTRY. 



Chief of Bureau, Beverly T. Galloway. 
Assistant Chief of Bureau, VfiLUAyi A. Taylor. 
Editor, J. E. Rockwell. 
Chief Clerk, James E. Jones. 



sell-bacteriology and w ater-purification investigations. 
Scientific Staff. 
Karl F. Kellerman, Physiologist in Charge. 
T. R. Robinson, Assistant Physiologist. 

I. G. McBeth, E. R. Allen, R. C. Wright, and Edna H. Fawcett, Scientific Assistants. 
F. L. Goll and L. T. Leonard, Laboratory Aids. 
211 
2 



]2]] 



LE^n^ER OF TRANSMITTAL 



U. S. Department of xioRicuLTURE, 

Bureau of Plant Industry, 

Office of the Chief, 
Washington, D. C, January 17, 191 L 
Sir: I have the honor to transmit herewith a paper entitled ''Bac- 
teriological Studies of the Soils of the Truckee-Carson Irrigation 
Project" and to recommend that it be published as Bulletin No. 211 
of the series of this Bureau. 

These investigations, though in many ways of a preliminary char- 
acter, indicate some of the possibilities of a bacteriological diagnosis 
of soils and will be of interest to all- who have to deal with problems 
of soil fertility. 

Respectfully, Wm. A. Taylor, 

Acting Chief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 
211 3 



CO NTH NTS, 



Page. 

Introduction 7 

Methods employed in bacteriological investigations of the soil at Fallon, Nev. . 8 

Requirements to be met 8 

founts of bacteria 9 

Ammonification 9 

Nitrification 10 

Denitrification 11 

Nitrogen fixation 11 

Nitrifying power of soils at different depths 12 

Nitrification of samples in solution 19 

Chlorids and sulphates 21 

Denitrification 22 

Relative numbers of bacteria in different soils 24 

Detailed study of soil typical of extensive areas 25 

Conclusions 32 

Index 35 



ILLUSTRATIONS. 



Page. 
Fig. 1. Location of sampling plats in the experimental fields of the Truckee- 

Carson Experiment Farm, south of Fallon, Nev 8 

2. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plats 100 and 110, Truckee-Carson 
Experiment Farm 12 

3. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 120, Truckee-Carson Experiment 
Farm 13 

4. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 130, Truckee-Carson Experiment 
Farm 13 

5. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plats 160 and 170, Truckee-Carson 
Experiment Farm 14 

6. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 180 (poor soil) and plat 190 (good 
soil), Truckee-Carson Experiment Farm 15 

7. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 200, Truckee-Carson Experiment 
Farm 16 

8. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 210, Truckee-Carson Experiment 

Farm 16 

211 5 



6 ILLUSTRATIONS. 

Page. 
Fig. 9. Diagram showing the nitrification of ammonium sulphate in samples of 
soil from different depths from plat 220, Truckee-Carson Experiment 
Farm 17 

10. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plat 230, Truckee-Carson Experiment 
Farm 17 

11. 1 )iagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plats 240 and 250, Truckee-Carson 
Experiment Farm IS 

12. Diagram showing the nitrification of ammonium sulphate in samples of 

soil from different depths from plats 260 and 270, Truckee-Carson 
Experiment Farm 19 

13. Diagram showing the nitrification of ammonium sulphate in samples of 

•soil from different depths from plats 280 and 290, Truckee-Carson 
Experiment Farm 20 

14. Diagram showing the relation between the quantity of alkali and the 

nitrification in samples of soil from plats 180, 190, 170, 150, 100, 160, 
110, and 120, Truckee-Carson Experiment Farm. Samples taken 
from depths of to 6 inches 21 

15. Diagram showing the relation between the quantity of alkali and the 

nitrification in samples of soil from plats 180, 120, 170, 100, 190, 150, 
160, and 110, Truckee-Carson Experiment Farm. Samples taken from 
depths of 6 to 12 inches 22 

16. Diagram showing the relation between the quantity of alkali and the 

nitrification in samples of soil from plats 180, 190, 170, 100, 120, 160, 
110, and 150, Truckee-Carson Experiment Farm. Samples taken 
from depths of 12 to 18 inches 23 

17. Diagram showing the relation between the quantity of alkali and the 

nitrification in samples of soil from plats 180, 170, 190, 100, 110, 160, 
150, and 120, Truckee-Carson Experiment Farm. Samples taken 
from depths of 18 to 24 inches 23 

18. Diagram showing the effect of calcium sulphate upon the nitrification 

of ammonium sulphate in samples of soil from plat 300, Truckee-Carson 
Experiment Farm, representing poor soil "A;" plat 310, representing 
poor soil "B;" and plat 320, representing good soil 29 

19. Diagram showing the ammonification of peptone in 7 days in samples of 

soil from plat 350 (good soil) and from plats 330 and 340 (poor soil), 
Truckee-Carson Experiment Farm 30 

20. Diagram showing the ammonification of peptone in 15 days in samples 

of soil from plat 350 (good soil) and from plats 330 and 340 (poor soil), 

Truckee-Carson Experiment Farm 31 

211 



B. P. I.— 646. 



BACTERIOLOGICAL STUDIES OF THE SOILS OF THE 
TKUCKEE-CARSON IRRIGATION PROJECT. 



INTRODUCTION. 

In making a bacteriological study of any soil or group of soils there 
are certain fairly well defined groups of micro-organisms whose func- 
tions, although as yet imperfectly understood, are recognized as im- 
portant factors in crop production and are more or less familiar to 
everyone who has attempted to investigate the problems of soil 
fertility. These groups of micro-organisms may be roughly separated 
into four classes, depending upon their physiologic characteristics: 
(1) Parasites, or organisms important chiefly because they are patho- 
genic to animals or plants and are frequently found in soils; (2) the 
cellulose-destroying organisms ; (3) the organisms associated with the 
formation of humus; and (4) the organisms associated with the trans- 
formation of soil nitrogen. Only those groups concerned with the 
transformation of nitrogen, which in the form of ammonia or nitrate 
is practically the most important of all plant foods, are reported upon 
at this time. 

The data sought in studies of this character may be outlined as 
follows: 

(1) Total numbers of saprophytic bacteria in measured quantities of soil. 

(2) Ammonification ; the breaking down of nitrogenous organic matter into ammonia. 

(3) Nitrification; the oxidation of various compounds of nitrogen to nitrate. 

(4) Denitrification; the reverse of nitrification. 

(5) Nitrogen fixation, symbiotic and nonsymbiotic; the utilization of atmospheric 
nitrogen in forming nitrogenous organic compounds. 

In the work conducted at Fallon, Nev., during the season of 1909, 
in cooperation with the Office of Western Agricultural Extension, no 
quantitative study was made of nitrogen fixation, and the data on the 
subject of ammonification are very meager. Some preliminary inves- 
tigations in arid regions had shown that nitrification takes place here 
at considerable depth. All studies, therefore, were made of a 3-foot 
zone, keeping separate the samples of soils from different depths. 

The comparative nitrifying power of the different samples from the 
various plats is shown by curves, the parts per million of nitrogen as 
nitrate and nitrite being plotted as ordinates, and the different depths 
as abscissae. These curves show only the gain in nitric and nitrous 
nitrogen. Chlorids and sulphates are also shown, but seem to be of 

211 7 



8 



SOILS OF THE TRUCKEE-CAKSON IRRIGATION PROJECT. 



little importance. The quantity of nitric nitrogen originally present 
is shown in the legends under the diagrams (figs. 2-13). 

A description of the Truckee-Carson Experiment Farm, at Fallon, 
Nev., upon which practically all of the work herein reported was con- 
ducted, is given in a previous bulletin of this Bureau.^ Tlie designa- 
tions of the small plats from which samples were taken for bacterio- 
logical study and their location are shown in figure 1 . 




Fig. 1.— Location of sampling plats in the experimental fields of the Truckee-Carson Experiment 

Farm south of Fallon, Nev. 

METHODS EMPLOYED IN BACTERIOLOGICAL INVESTIGATIONS 
OF THE SOIL AT FALLON, NEV. 



REQUIREMENTS TO BE MET. 

Investigations in soil bacteriology require first of all the selection 
and development of satisfactory methods for determining the dis- 
tribution and activity of the micro-organisms which may occur under 

' Scofield, C. S., and Rogers, S. J. The Truckee-Carson Experiment Farm. Bul- 
letin 157, Bureau of Plant Industry, 1909. 
211 



METHODS EMPLOYED IN BACTERIOLOGICAL INVESTIGATIONS, 9 

different soil conditions. Though it is recognized that the methods 
suggested by different investigators are not adequate for accurate 
quantitative investigations of bacterial functions and conditions in 
various soils, the methods which at this time have been found most 
convenient and suitable for the investigations under discussion are 
briefly reviewed.^ 

COUNTS OF BACTERIA. 

Samples of soil were collected with as strict aseptic precautions as 
it is possible to observe under field conditions. Sterile salt-mouth 
bottles were used as containers, and the soil auger used for taking up 
the soil was carefully cleaned and flamed over an alcohol lamp before 
sampUng each stratum. In the laboratory 1-gram portions were 
removed from the bottles with a sterile scoop wliich held the required 
quantity, transferred to 300 cubic centimeters of sterile water in 
500-cubic-centimeter flasks, and the whole shaken thoroughly at short 
intervals for fifteen minutes. One-cubic-centimeter portions of these 
infusions were then removed with sterile pipettes and added to 10 
cubic centimeters of melted beef agar, and plates poured in the ordi- 
nary manner and incubated at 28° C. Counts of bacteria were made 
at the end of five-day periods. 

AMMONIFICATION. 

Sterile peptone solutions having the following composition were 
inoculated with 5 per cent of soil and the ammonia determined at the 
end of seven and fifteen days by distillation with magnesia: 

Peptone 15 grams. 

Dipotassium phosphate 3 grams. 

Magnesium sulphate 3 grams. 

Sodium chlorid 3 grams. 

Water ] , 000 c. c. 

^ Lipman, J. G. Experiments on the Transformation and Fixation of Nitrogen by 
Bacteria. Twenty-fourth Annual Report, New Jersey State Agricultural Experiment 
Stations, 1903, pp. 217-285. 

Lipman, J. G., and Brown, Percy E. Methods Concerning Ammonia Formation 
in Soils and Culture Solutions. Report, Soil Chemist and Bacteriologist, New Jersey 
Agricultural College Experiment Station, 1908, pp. 95-105. 

Lipman, J. G., and Brown, Percy E. Notes on Methods and Culture Media. Report, 
Soil Chemist and Bacteriolflgist, New Jersey Agricultural College Experiment Station, 
1908, pp. 129-136. 

Lipman, J. G. Azotobacter Studies. Report, Soil Chemist and Bacteriologist, 
New Jersey Agricultural College Experiment Station, 1908, pp. 137-143. 

Lohnis, F. Ein Beitrag zur Methodik der bakteriologischen Bodenuntersuchung. 
Centralblatt fiir Bakteriologie, Parasitenkunde und Infektionskrankheiten, pt. 2, 
vol. 12, no. 6-8, pp. 262-267, June 24, 1904; no. 11-16, pp. 448-463, July 14, 1904; 
vol. 17, no. 14-16, pp. 518-528, December"?, 1906; vol. 20, no. 24-25, pp. 781-799, 
April 15, 1908; vol. 24, no. 5-7, pp. 183-192, August, 1909. 

Remy, Theodor. Bodenchemische und Bakteriologische Studien. Landwirt- 
schaftliche Jahrbiicher, vol. 35, Supplement 4, pp. 1-62. Berlin, 1906. 
78011°— Bui. 211—11 2 



10 SOILS OF THE TEUCKEE-CARSON IKRIGATION PROJECT. 

NITRIFICATION. 

Samples of soil were collected with the precautions previously 
described. In some cases 1-gram portions for counts of total num- 
bers of bacteria were removed from the bottle of soil and the remainder 
of the sample used for nitrification studies. 

Because of the great variation in the fertilty of different fields it 
was considered necessary to determine at what depths the nitrifying 
bacteria existed; therefore, instead of emptying the soil from the 
container and allowing it to dry, thus exposing it to some contamina- 
tion, one-half of the soil, approximately 50 grams, was removed with 
a sterile spatula and used for "original" determinations. Five cubic 
centimeters of 0.4 per cent ammonium sulphate was then added to the 
portion remaining in the bot Je and the sample placed in the incu- 
bator at 28°C. With the original moisture of the soil this additional 
5 cubic centimeters frequently made the water content of the soil 
somewhat above optimum, but owing to the rapid evaporation in an 
arid climate this rapidly decreased and was adjusted as nearly as 
possible in subsequent waterings. All samples were weighed at S-da}^ 
intervals, and as any appeared to fall below optimum the required 
quantity of sterile distilled water was added to restore them. The 
incubation period was two weeks, the temperature being maintained 
at 28°C. 

The chemical work presented no little difficulty. The analytical 
determinations may be considered in two phases: (1) The prepara- 
tion of the aqueous extract of the soil both before and after incuba- 
tion with ammonium sulphate and (2) the determination of nitrites 
and nitrates in original and incubated samples. 

In the preparation of the aqueous extract considerable difficulty 
was experienced. AU of the soils used contained variable and fre- 
quently quite large proportions of very fine clay, which would not 
settle out and leave a clear supernatant liquid, even on prolonged 
standing. It was thought advisable to determine the chlorids and 
sulphates in the original samples; therefore the common salts con- 
taining these radicals could not be used to flocculate the clay, 
although this method was sometimes used in the examination of the 
samples after incubation where only nitrites and nitrates were deter- 
mined. Pressure-pump facilities were inadequate for the large num- 
ber of samples used, the more so as the fine clay particles clogged the 
porcelain filter and caused filtration to be extremely slow with the 
low pressure available.* Heating the sample in the oven at different 
temperatures previous to adding the water seemed to have no effect, 
so the supernatant liquid was first drawn off turbid, evaporated to 
dr;yness, baked at 90° to 100° C, and then filtered. In all of the 

' Approximately 25 pounds to the square inch. 
211 



METHODS EMPLOYED IN BACTEKIOLOGICAL INVESTIGATIONS. 11 

baking experiments it was noticed that the nearer a set of samples 
was baked at 100° C. the better the subsequent filtering, probably 
indicating that the clay is siliceous. 

The Griess method is the standard for determining nitrites, but 
owing to the delay in getting chemicals at Fallon the potassium- 
iodid-starch method was used for a large part of the work. This 
method, while primarily a quahtative one, was found to be fairly 
reliable for quantitative determinations if a large quantity of reagent 
was used when the nitrites were high, as indicated by a rapid develop- 
ment of the blue-black color. The Grandval-Lajoux phenol-sulphonic 
acid method as modified by Syme ^ was used for estimating -nitrates; 
before determining nitrates the nitrites were removed by urea in acid 
solution in accordance with Piccini's method. 

Chlorids were frequently high in soil solutions in wliich nitrates were 
to be determined, and it was necessary to remove them when present 
in concentrations greater than 50 or 70 parts per million. This was 
accomplished by the use of silver sulphate. 

Chlorids ^ were determined by the Mohr method, titrating the 
neutral solution with N/10 silver nitrate and using potassium chromate 
as an indicator. Sulphates ^ were determined by the turbidity 
method described by the Bureau of Soils.^ 

DENITRIFICATION . 

Studies of denitrification were made by inoculating Dunham's 
peptone solution containing 0.2 per cent potassium nitrate with soil 
and with a Frost scale measuring roughly the quantity of free nitrogen 
evolved. Either ordinary fermentation tubes or test tubes inverted 
in salt-mouth bottles were used. The latter method is preferred, as 
it permits the use of larger quantities of soil for inoculations. 

NITROGEN FIXATION. 

Leguminous plants were examined for the presence of nodules, and 
Azotobacter cultures were isolated from soil samples. 

• Syme, W. A. The Oolorimetric Determination of Nitrates in Soil Solutions Con- 
taining Organic Matter. Thirty-first Annual Report of the North Carolina Agricul- 
tural Experiment Station, for the Year Ending June 30, 1908, pp. 64-65. 

2 Both of these salts were determined by Mr. C. A. Jensen, of the Office of Western 
Agricultural Extension of the Bureau of Plant Industry. 

^ Schreiner, Oswald, and Failyer, George H. Colorimetric, Turbidity, and Titration 
Methods Used in Soil Investigations. Bulletin 31, Bureau of Soils, U. S. Dept of 
Agriculture, 1906. 
211 



12 



SOILS OF THE TEUCKEE-CARSON IRRIGATION PROJECT. 



NITRIFYING POWER OF SOILS AT DIFFERENT DEPTHS. 

In investigations in soil bacteriology in the eastern United States 
only the surface soil shows great variations. The soil of the arid 
sections is much deeper, however; that is, the subsoil is less ''raw" 
than in regions of heavier rainfall, a fact that has come to be more 
or less famiUar to everyone studying soil conditions over extensive 
areas. 

Figure 2 shows the nitrification of samples from plats 100 and 110. 
These plats, which are practically duplicates, are in a })roductive 




Fig. 2. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats 100 and 110, Truckee-Carson Experiment Fann. Original nitrate present in samples from 
plat 100: Depth, to 6 inches, 8 parts per million; to 12 inches, 15; 12 to 18 inches, 9; 18 to 24 inches, i.S; 
24 to 36 inches, 6.5(i. From plat 110: Depth, to 6 inches, 9 parts per milhon; 6 to 12 inches, 7.4; 12 to 
18 inches, 5.2; 18 to 24 inches, 4.8; 24 to 30 inches, 3.12. 

alfalfa field which has been under cultivation for several years. The 
soil is loose and sandy throughout the 3-foot depth. The nitrate 
curves show that there is a gradual decrease in nitrifying power with 
depth. 

Figures 3 and 4 show the nitrification in samples from plats 120 and 
130. These are in a fertile alfalfa field similar to the one mentioned 

211 



NITRIFYTNd POWER OF SOILS AT DIFFERENT DEPTHS. 13 



90 L 



% 


80 




70 


k 




^ 




> 


60 


Si 




^ 




I 


50 


% 




\ 


40 


^ 




<>> 




N, 


30 


Nl 




« 




f^ 


20 


Si 




14! 




T\ 


10 


K 




1^ 




^ 







-10 



,Qiro^' 6"rol2" l2>ol8" \&'ro24' 24'>»36" 



~ ~-— - /i(tC(tt'l-6la/J. ??— - 




; )(i/phares:M:^fj^ '^ -—CMor/ctk -P/at/2o 



900 


^ 


ROO 


1 




.^ 




vo 


700 


1 




^ 


600 


^ 




\ 


fiOO 


^ 




I 


400 


\ 




^ 


300 


1 




M 


200 


1 




^ 


100 


u! 




jn 




k 





lir 




5 


-100 





Fig. 3.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 120, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to G 
inches, 15.36 parts per million; 6 to 12 inches, 8.64; 12 to 18 inches, 6.72; 18 to 24 inches, 3.84; 24 to 36 inches, 
2.88. 

in the previous paragraph. The samples from plat 120 show nitrifica- 
tion varying rather irregularly with depth. Samj:)les from plat 130 






10 



— 



Si'ro&' €'7vlZ" I270I8" l8'7o24' 24ro36" 







200 ^1 

100 II 
^§ 



Fig. 4.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 130, Tnickee-rarson Experiment Farm. Original nitrate present in samples: Depth, to (> 
inches, 13.3 parts per million; (i to 12 inches, 6.72; 12 to 18 inches, 9.6; 18 to 24 inches, 7.23; 24 to 36 inches, 
14.4. 



14 



SOILS OF THE TEUCKEE-CARSON IBEIGATION PROJECT. 



practically failed to nitrify,^ although the two plats appear to be very 
similar. 

Figure 5 shows the relative nitrifying power of good and poor soils 
collected from adjoining plats. Plat 160 has a loose sandy soil to a 




Fig. 5. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats IdO and 170, Truekee-Carson Experiment Farm. Original nitrate present in samples from 
plat KX): Depth, to (i inches, 8.04 parts per million; to 12 inches, 2.88;"12 to IS inches, 4.8; 18 to 24 inches, 
G; 24 to 30 inches, 4.8. From plat 170: Depth, to inches, 4.32 parts per million; 6 to 12 inches, 0; 12 to 
18 inches, 3.84; 18 to 24 inches, 3.0; 24 to 30 inches, 3. 

depth of 18 inches; below this it is very heavy, but below 26 and 30 
inches it is again lighter in texture. At the time of sampling, this 
plat was supporting a fine growth of alfalfa. Plat 170 is in the north- 
east corner of the same field, and was very similar except that the 

' This field had been irrigated a short time' before the samples were collected. 
211 



KiTElFYlKG POWER OF SOILS AT DIFFERENT DEPTHS. 



15 



surface was a little more compact and the alfalfa was practically a 
failure. The nitrification curves show the same general variations, but 
the one of the poor soil is consistentl}^ below that of the productive soil. 




Fig. 6.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 180 (poor soil) and plat 190 (good soil), Truckee-Carson Experiment Farm. Original nitrate 
present in samples from plat 180: Depth, to 6 inches, 2 parts per million; 6 to 12 inches, 3.5; 12 to 18 
inches, 8.25; 18 to 24 Inches, 4.5; 24 to 36 inches, 25.75. From plat 190: Depth, to 6 inches, 4.5 parts per 
mimon; 6 to 12 inches, 15.75; 12 to 18 inches, 11.25; 18 to 24 inches, 20.75; 24 to 36 inches, 21.75. 

Plats 180 and 190 are located upon poor and good spots. The 
texture of the samples is very similar, both being sandy, but the 
surface of plat 180, the unproductive soil, is hard and compact as if 

211 



16 



SOILS OF THE TEUCKEE-CAESON TREIGATTON PROJECT. 



held together by some cementing material. As shown in figure 6, the 
nitrifying power of samples from plat 180 is almost nothing. In this 
figure the chlorid and sulphate curves are of interest, as those of plat 
180, the poor soil, are far above those of plat 190, the good soil.^ 




Fig. 7.— Diagram showing tlie nitrification of ammonium sulphate in samples of soil from different depths 
from plat 200, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to G 
inches, 7.68 parts per million; 6 to 12 inches, 5.8; 12 to 18 inches, 3.93; 18 to 24 inches, 4.32; 24 to 36 inches, 
1.82. 

Figures 7 to 10, inclusive, show the nitrifying power of samples of soil 
from plats 200, 210, 220, and 230. They are in fields which have only 
recently been leveled and irrigated; in fact, 1909 was the first year 
they had been cropped. They produced a fair crop of barley, but the 



.d'Tve' errlZ" I2'^I8" I8"7d24" 24to36" 




200 k, 


.00 i 


^j5c 


«a* 


" f*s 


^0) 


-100 kJ 


Q: 


5 



Fig. 8.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 210, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to (i 
inches, 2.66 parts per million; 6 to 12 inches, 4.8; 12 to 18 inches, 4.16; 18 to 24 inches, 3; 24 to 36 inches, 2. 

young alfalfa sown in the barley was doing only fairly well. The 
curves from all of these plats show a very low nitrifying power, yet a 
glance at the figures shows that nitrates were present in moderate 
quantities in the original samples. 



Bridge readings on these samples were made by Mr. Jensen. 



211 



NITKIFYING POWEE OF SOILS AT DIFFERENT DEPTHS. 



17 



Figures 11 and 12 present the results obtained from samples of soil 
from plats 240, 250, 260, and 270. The fields in which these plats are 



i 




^ 


4-0 


* 




^ 




^ 


30 


^ 




vS 




<s> 




t^ 


20 


$ 




J< 






10 


^ 




Nl 








^ 





^ 




{? 


-10 


Or- 




^ 





DEPTH ^T W/¥/C/¥ S/JMPLES W£P£ T/JH-fA/. 
.0'n?6" 6rol2" I2'n7l8" I8ro24" 24'n?36" 



— - — .^alBllS^^^ 



PlatZjiL'. ' 



+^^S2J*:^^A 




A//Wfes-fVa'220 



400 



300 



200 



(00 



100 



Fig. 9.— Diagram showing tlie nitrification of ammonium sulphate in samples of soil from different deptiis 
from plat 220, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to 6 
inches, 7.68 parts per million; H to 12 inches, (i. 91; 12 to 18 inches, 10; 18 to 24 inches, 5. (i4; 24 to 36 inches, 6. 

located have been merely leveled and left fallow, receiving regular 
applications of irrigation water. The field containing plats 240 and 
250 is never cultivated, while that containing plats 260 and 270 is 




Fig. 10. — Diagram showing the nitrification of anunonium sulphate in samples of soil from different depths 
from plat 230, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to li 
inches, 10 parts per million; 6 to 12 inches, 8. IG; 12 to 18 inches, S; 18 to24inches,4.5(i; 24 to 36 inches, 9. li. 

cultivated according to thorough summer-fallow metliods. As the 
conditions are abnormal it is not surprising that the curves of chlorids 
78011°— Bui. 211—11 3 



18 



SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 



and sulphates, as well as the curve showing nitrification, should be so 
erratic and variable. 

Figure 13 shows the nitrifying power of samples from plats 280 and 




Fig. U.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats 240 and 250, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 240: Depth, to 6 inches, 6.8 parts per million; 6 to 12 inches, 8; 12 to 18 inches, 10.4; 18 to 24 inches, 
C; 24 to 36 inches, 5. From plat 250: Depth, to 6 inches, 28 parts per million; 6 to 12 inches, 48; 12 to 
18 inches, 6; IS to 24 inches, 5.2; 24 to 36 inches, 7. 

290, located in an old alfalfa field just north of Fallon. These soils 
are ver}^ productive, and it was expected that they would show 
a greater nitrifying power than thev did. This mav possibly be 

211 



NITRIFICATION OF SAMPLES IN SOLUTION. 



19 



explained, however, by the original high nitrate content of the soil, 
as there is often a tendency for the nitrifying power of a soil to 
decrease as nitrates accumulate. 

NITRIFICATION OF SAMPLES IN SOLUTION. 

In order to further test for the presence of nitrif:vang bacteria and 
also to study some of their characteristics, inoculations were made 




Fig. 12.— Diagram showing the nitriflcation of ammonium sulphate in samples of soil from different depths 
from plats 2G0 and 270, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 2G0: Depth, to 6 inches, 02 parts per million; to 12 inches, 30; 12 to 18 mches, 18.75; 18 to 24 
inches, 35.7; 24 to 3G inches, 30. From plat 270: Depth, to inches, 100 parts per milUon; 6 to 12 
mches, 27.7; 12 to 18 inches, 50; 18 to 24 inches, 40; 24 to St; inches, 50. 

into media consisting entirely of inorganic material wliich is not suit- 
able for the growth of saprophytic bacteria. ^ Curves have not been 
plotted from the data thus obtained, as the conditions were too 
abnormal to warrant considering the differences from a quantitative 

» Winogradsky and Omelianski's Fluid Culture-Medium for Isolating the Nitrate 
Bacteria from Soils, and Winogradsky and Omelianski's Fluid Culture-Medium for 
Isolating the Nitrite Bacteria from Soils. Centrallilatt fiir Bakteriologie, Parasiten- 
kunde und Infektionskrankheiten, vol. 5, pt. 2, 1899, pp. 537-549. 
211 



20 



SOILS OF THE TEUCKEE-CAESON lEEIGATION PEOJECT. 



standpoint. The results are all expressed in Table I as parts of 
nitrogen per million of the solution. 




Fig. 1.3. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
Irom plats 280 and 290, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 280: Depth, to (i inches, 12 parts per million; 6 to 12 inches, 10; 12 to IS inches, 6; 18 to 24 inches, 
15; 24 to 36 inches, 02.5. From plat 290: Depth, to 6 inches, GO parts per million; li to 12 inches, (iO; 
12 to 18 inches, 55.4; 18 to 24 inches, 60; 24 to 36 inches, 00. 

Table I. — Nitrification in solution of samples of soil from plats 100. 110. 180, 190, 220, 
260, 270, and 280,^ Truckee-Carson Experiment Farm. Incuhated^al 28° C. 







Ammonia to nitrite 


Nitrite to nitrate 




Depth 
of soil. 


(parts per million V^ 


(parts per million) » 


plat. 










) 






6 days. 


12 days. 


10 days. 20 days. 




Inches. 


1 . 






100 


0-6 


(i. 50 


25 


91.60 


9t;. 00 




6-12 


5.00 


25 


64.80 


60.00 




12-18 


6.50 


18 


86.40 


81.60 


110 


0-6 


.50 


15 


1 


180 


(J-12 
12-18 
0-6 


3.25 
8.00 
0.00 


20 
25 

15 


... 1 






24 00 


86.40 




()-12 


0.00 1 15 


3.60 


2.40 




12-18 


0.00 : 00 


2.40 


3.00 


190 


0-6 


1.00 16 


72.00 


74.00 


220 


0-6 


0.00 00 


13.20 


SO. 00 




6-12 


0.00 00 


3.60 


5.32 




12-18 


0.00 00 


2.40 


5.60 


260 


0-6 


.5.00 17 


76.80 


74.00 




(1-12 


3. 00 ' 10 


57.60 


54.40 




12-18 


3. 00 1 10 


2.88 


17.55 


270 


0-6 


6. 50 20 


9.60 


43.20 




6-12 


0.00 00 


8.64 


■ 60.00 


2801 


0-6 


5. 75 , 20 


21.60 


81. 60 




6-12 


1.00 20 


40.80 


81.60 




12-18 


1.00 20 


38.40 


81.60 



1 Plat 280 is located in an old alfalfa field one-fourth mile north of Fallon. 

2 Used medium for isolating nitrite bacteria. ^ Used medium for isolating nitrate bacteria. 

211 



CHLORIDS AND SULPHATES. 



21 



It will be seen that the nitrifiers and especially the nitrate bacteria 
develop quite well in solutions. It should be noted that the only 
samples that failed to produce nitrites were those taken at 6-inch, 
12-inch, and 18-inch depths from plat 220, which failed to nitrify in 
soil. (See fig. 9.) This soil, however, produced nitrates quite readily. 
This suggests tlie possibility that the lack of nitrification in this soil 
may be due to lack of nitrite bacteria. 

CHLORIDS AND SULPHATES. 

In alkali studies it is recognized that as a rule the chlorid type is more 
injurious to ordinary farm crops than the sulphate type. Further, in 
some investigations in the soils of the arid regions it has been found 



«j875 

1 

^75.0 
m37.5 

1 

^25.0 
$12.5 


ISO 190 170 150 100 160 110 120 


1225 V) 
1050 IJi 
875 ^ 

1 

700 J 
525 1 

Nl 

1 

350 ft 

175 ^ 
















^ 
















/ 


















/ 












jjitrgjs^ 
















/ 


















/ 






~^'^^^^. 


\ 










c 


"Z^^ 


'^jjorids:- 


' 


\ 


^> 







Fig. 14.— Diagram showing the relation between the quantity of all^:ali and the nitrification in samples of 
soil from plats 180, 190, 170, 150, 100, HiO, 110, and 120, Tnickee-Carson Experiment Fami. Samples 
taken from depths of to inches. 

that high nitrates correlate with the sulphate type, while low nitrates 
are usually associated with the chlorid type. It was thought, tliere- 
fore, that it would be of interest in connection with this work to study 
the relation of chlorids and sulphates to the nitrifying power. 

In plotting these curves the different plats are arranged in such 
an order that the nitrification of ammonium sulphate by the dif- 
ferent samples, which is the index of the difference of their powers 
of nitrification, forms an ascending series. Four diagrams are pre- 
sented (figs. 14 to 17), one for each depth from which samples of soil 
were taken. Figure 14, representing the surface samples, shows no 
relation between the concentration of soluble salts and nitrifying 
power. Figures 16 and 17, representing the deeper samples, are 

211 



22 



SOILS OF THE TEUCKEE-CARSON IRRIGATION PROJECT. 



not in close agreement, although high alkali consisting of both 
chlorids and sulphates is apparently correlated mth low nitrification. 
Little if any difference is to be noted between the effect of the chlorid 
and the sulphate types of alkali. 



DENITRIFICATION. 



In order to test for the presence of denitrifying bacteria several 
inoculations were made into Dunham's solution containing 0.2 per 



875 
75.0 
$62.5 
^50.0 
|37.s 
^250 

1 ° 


180 120 170 100 190 150 160 110 


1 

1050$ 

875"^ 

700 § 


525^ 
350 1 

-0 




1 
\ 
I 


















\\ 
U 
U 

V 


















Vl 
U 

V 

\\ 
\> 
\\ 


















V 








^ 




y^ 






\ 


/ 


■v . 

\ 

\ 


02i>^ 










/ 






/ 
/ 

/ 
/ 
/ 
/ 




N 














/ 


c/" 


\\.^ 


SUjg'l''JSi 




'■V 

























Fig. 15.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
soil from plats 180, 1'20, 170, 100, 190, 150, IfiO, and 110, Truckee-Carson Experiment Farm. Samples 
taken from depths of tl to 12 inches. 

cent of potassium nitrate, and the free nitrogen gas evolved was 
measured. This medium favors the growth of tliis class of bacteria. 
The conditions thus produced are abnormal and the quantitative 
differences shown in Table II should not be taken too seriously. It 
will be seen from the table that denitrifying bacteria are present and 
active in almost all of the soils tested. 

211 



DENITRIFICATION. 



23 




Pig. 16.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
soil from plats ISO, 190, 170, 100, 120, 160, 110, and 150, Truckee-Carson Experiment Farm. Samples 
taken from depths of 12 to 18 inches. 



lOOo 

^ 75.0 
^62.5 

1 

^ 50.0 
|375 
(V 25.0 

g,2.s 

1 




180 (70 190 100 110 160 150 120 


1400 
1225 1 
1050^ 
875 Q 
700 ^ 

525 1 

1 
3S0| 

175 ^ 


























\ 

\ 
\ 

\ 


















\ 
\ 
\ 

\ 


















\ 

\ 

\ 
\ 
\ 


















\ 
\ 


1 


















\ 








^ 






V 
T 




\ 

\ 
\ 
\ 
\ 






/ 












\ 


/V/frates 


-^ 


















^^ 


<Lfe*^ 


"^•» 


::^ 






^^^ 




/^ 















Fig. 17.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
soil from plats 180, 170, 190, 100, 110, 160, 150, and 120, Truckee-Carson Experiment Farm. Samples 
taken from depths of 18 to 24 inches. 
211 



24 



SOILS OP THE TRUCKEE-CARSON IRRIGATION PROJECT. 



Table II.- 



Denitriji cation in solution of samples of sml from plats 180. 190. 2S0, 260, 
270. 280,^ and 290,^ Truckcc- Carson Experiment Farvi. 



No. of 


Depth of 


Gas formed 


Gas formed 


plat. 


soil. 


in 7 days. 


in 15 days. 




Inches. 


Per cent. 


Per cevt. 


180 


0-6 


25 


25 




6-12 


20 


30 




12-18 


20 


25 


190 


0-6 


22 


32 




6-12 


30 


40 




12-18 


32 


42 


2.30 


0-6 


20 


30 




6-12 


21 


30 




12-18 


20 


35 


260 


0-6 


40 


53 




6-12 


15 


23 




12-18 


20 


30 


270 


0-6 


20 


30 




6-12 


20 


30 




12-18 


20 


30 


280' 


0-6 


00 


00 




6-12 


Trace. 


Trace. 




12-18 


Trace. 


Trace. 


2901 


0-6 


22 


40 




6-12 


10 


18 




12-18 


45 


62 



' Plats 280 and 290 are located in an old alfalfa field one-fourth mile north of Fallon. 
RELATIVE NUMBERS OF BACTERIA IN DIFFERENT SOILS. 

An estimation of the number of bacteria in a gram of soil that 
would develop aerobically upon beef agar was made for many of the 
sampling plats in accordance with the method previously described, 
the results of which are shown in Table III. In accord with the 
reports of other investigators, ^ the data presented in Table III 
clearly show that the numbers of bacteria found in the different 
samples bear no consistent relation to the fertility or crop-producing 
power of the respective fields. 

No attempt was made to determine the relative numbers of proto- 
zoa in samples of soil from the good and })oor areas. If the develop- 
ment of protozoa is determined by their food supply,' in other words, 
by the numbers of bacteria existing in the soil, it is obvious that in this 
region the crop-producing power can not be limited ^ by the abundance 
of protozoa. 

' Lohnis, F. Ein Beitrag zAir Methodik der bakteriologischen Bodenuntersuchung. 
Centralblatt fiir Bakteriologie, Parasitenkunde und Infektionskrankheiten. pt. 2, 
vol. 12, no. 6-8, June 24, 1904, pp. 262-267. 

Chester, Frederick D. The Bacteriological Analysis of Soils. Bulletin 65, Dela- 
ware College Agricultural Experiment Station, March 1, 1904. 

Voorhees, Edward B., and Lipman, Jacob G. A Review of Investigations in Soil 
Bacteriology. Bulletin 194, Office of Experiment Stations, U. S. Dept. of Agriculture, 
October 26, 1907. 

- Russell, E. J., and Hutchinson, H. B. The Effect of Partial Sterilization of Soil 
on the Production of Plant Food. Contributions from the Laboratory of the Rotham- 
sted Experimental Station, October, 1909, pp. 111-144. 

■' Hall, A. D. The Fertility of the Soil. Science, n. s., vol. 32, no. 820, September 
16, 1910, pp. 363-371. 
211 



DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 



25 



Table III. — Number of bacteria 'per gram of soil and nitrifying power of samples from 
plats 10, 20. 30, 40, 180, 190, 290,^ 240, 260, and 270, Trucl-ee-Carson Experiment 
Farm. 









Nitrifying 




No. of 
plat. 


Depth of 
soil. 


Number of 
bacteria per 


power of 
soils (parts 


Character of soil. 




gram. 


per mil- 










lion). 






Inchex. 








:o 


0-6 


435,000 


4.4 


Very poor. 




6-12 


251,000 


2.0 






12-18 


26, 650 


.0 






18-24 


146,250 


3.0 






24-36 


1,000 


.0 




20 


0-6 


19,500 


54.2 


Very productive. 




6-12 


11,250 


6.8 


Good growth of 




12-18 


30,000 


1.0 


alfalfa. 




18-24 


4,500 


.0 






24-36 


3,000 


.0 




30 


0-6 


160,000 


3.0 


Poor and com- 




6-12 


65,000 


.0 


pact. 




12-18 


262,000 


.0 






18-24 


19, 855 


.0 






24-36 


10,000 


.0 




40 


0-6 


210,000 


20.4 


Productive. 




6-12 


20,000 


4.0 


Good growtli of 




12-18 


135, 000 


1.0 


alfalfa. 




18-24 


45, 000 


.0 






24-36 


1,000 


.0 




180 


0-6 


60,000 


4.72 


Very poor. 




6-12 


175, 000 


1.54 


Alkali higli. 




12-18 


180,000 


4.32 


(See fig. 6.) 




18-24 


4,000 


2.54 




190 


0-6 


3,600 


36.30 


Productive. 




6-12 


168,000 


37.45 






12-18 


1,554,000 


12. 75 






18-24 


704,000 


12.25 




290' 


0-6 


273,000 


30.00 


Productive. 




6-12 


396,000 


20. 00 


Old alfalfa fielfl. 




12-18 


262, 500 


14.60 


(Seeflg. 13.J 




18-24 


327, 000 


4.00 




240 


0-6 


52, 000 


69.00 


Fallow. (See 




6-12 


78, 700 


4.50 


fig. 11.) 




12-18 


56,000 


.40 




260 


0-6 


81,000 


18.00 


F a 1 1 w. (See 




6-12 


153,300 


40.00 


fig. 12.) 


270 


0-6 


72,000 


100.00 






6-12 


2,790,000 


92. 30 





' Plat 290 is located in an old alfalfa field one-fourth mile north of Fallon. 

DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 

Plats 300 to 350 are representative of a somewhat extensive type 
of soil of the Truckee-Carson project. This soil is very unproductive 
as a rule, almost barren in many cases, yet all through it, wherever 
properly leveled and irrigated, are spots of a few square rods in area 
that are normal and productive. The difference between these two 
conditions seemingly can not be explained by any of the now known 
causes of infertility. There is a certain difference in texture, or rather 
in the physical properties; the productive soil is loose and sandy, 
while the unproductive type, although sandy, contains a small quan- 
tity of clay which when shaken up with water remains suspended 
indefinitely and the soil cements on drying. These physical differ- 
ences, while no doubt factors, do not seem adequate causes of the 
extremely low fertility. The total alkah content is not high enough 

211 



26 SOILS OF THE TEUCKEE-CAKSON IRRIGATION PROJECT. 

to produce toxic effects, and a lack of mineral plant food in the virgin 
soils is almost out of the question. 

Both soils are' low in organic matter, as are all arid soils. Good 
soil management in other somewhat similar regions would indicate 
that the addition of organic matter to these soils in the form of barn- 
yard manure or green manure should produce beneficial physico- 
chemical effects, and such treatments have been applied somewhat 
extensively as a matter of experiment during the last two or three 
years. The poor soil apparently has not been benefited to a noticea- 
ble degree. The good soil has been somewhat improved, although 
even here the improvement has not been striking. A minute field 
examination of these good and poor spots a year or more after they 
had received applications of organic matter revealed a remarkable 
difference; all traces of the organic material had disappeared from 
the fertile spots, while the larger part of the manure added to the 
infertile spots was in an almost perfect state of preservation. Another 
peculiar difference was that in the poor spots, at depths of 6 to 28 
inches, an irregularly distributed, dark-colored, foul-smelling layer 
was found, undoubtedly due to the presence of a peculiar organic 
decomposition product, while such a layer was never found associated 
with good soil. It should not be inferred from this description that 
this black layer was found only where organic matter has been added 
as a treatment; it was quite generally distributed through these 
infertile soils and is presumably due to the decay of such material as 
was turned into the soil when it was first reclaimed, such as sagebrush, 
greasewood, rabbit brush, and other desert plants, together with the 
roots of these plants which have been accumulating for long periods 
of time. Laboratory samples showed that this black substance was 
easily oxidized, for when a sample was taken to the laboratory, dried, 
and subsequently moistened for physiological experiments, all traces 
of the black color and peculiar odor disappeared. 

These unusual conditions of the decay of organic matter are neces- 
saril}^ somewhat closely associated with improper bacteriological 
conditions; that is, the improper utilization of organic fertilizers is 
due either to an improperly balanced or incomplete bacterial flora 
or to physical or chemical conditions preventing the performance of 
the normal activities of the bacteria present. 

Titrations of some of the aqueous extracts indicated that sodium 
carbonate (black alkali) was present in the poor soils but not in the 
good soils. It was also apparent that calcium sulphate and gypsum, 
when applied in large quantities, produced a decided effect in floc- 
culating the finely divided or colloidal clays. Samples were collected 
with a sterile spatula from the sides of freshly dug holes and placed 
in sterile containers. Portions of these samples were inoculated into 
'Ml 



DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AEEAS. 



27 



Winogradsky's solutions and also into flasks of sterile water, from 
which counts were made. The remaining portions of the samples 
were then emptied on clean sheets of paper in the culture room and 
left to dry under conditions as free as possible from chance contami- 
nations. Fifty-gram portions from each sample were removed for 
original nitrate determinations, and another equal portion was re- 
placed in the original containers, brought up to optimum moisture 
content with 5 cubic centimeters of 0.4 per cent sulphate of ammonia 
and distilled water, incubated for two weeks at 28° C, and the nitri- 
fication determined. A duplicate series to which was added a 2 per 
cent solution of calcium sulphate was prepared. At the beginning 
of the incubation period the total weight of the container and soil 
at optimum moisture was taken, and the loss from evaporation was 
restored with sterile distilled water at 3-day intervals during the 
incubation period. The results of the experiment appear in Tables 
IV and V. 



Table 1\ .^Effect of calcium sulphate upon nitrification in samples of soil from plats 
300 and SIO, Truckee- Carson Experiment Farm, representing poor soil conditions. 
Incubated 15 days at 28° C. 

NO CALCIUM SULPHATE ADDED TO SAMPLES. 



No. of 
plat. 

300 
310 


Depth of 
soil. 


Nitrogen as nitrite (parts per 
million). 


Nitrogen as nitrate (parts per 
million). 


Original. 


Final. 


Gain. 


Original. 


Final. 


Gain. 


Inches. 
0-6 
6-12 
12-18 
18-24 
0-6 
6-12 
12-18 
18-24 


1.2 
2.0 
1.2 
.0 
1.0 
1.0 
1.0 
1.0 


5.60 
3.12 
1.68 
1.20 
7.28 
2.10 
.80 
1.20 


4.40 
1.12 

.48 

1.20 

6.28 

1.10 

- .20 

.20 


9.12 
7.68 
6.14 
4.56 
4.80 
1.60 
4.32 
3.07 


56.40 
00.00 
00.00 
00.00 
96.00 
00.00 
00.00 
00.00 


46.28 

- 7.68 

- 6.14 

- 4.56 
91.20 

- 1.60 

- 4.32 

- 3.07 



WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 



300 


0-6 


1.2 


2.80 


1.60 


9.12 


57.00 


47.88 




6-12 


2.0 


2.80 


.80 


7.68 


00.00 


- 7.68 




12-18 


1.2 


2.70 


1.50 


6.14 


00.00 


- 6.14 




18-24 


.0 


.88 


.88 


4.56 


00.00 


- 4.56 


310 


0-6 


1.0 


4.00 


3.00 


4.80 


96.00 


91.20 




6-12 


1.0 


2.40 


1.40 


1.60 


1.20 


- .40 




12-18 


1.0 


1.68 


.68 


4.32 


0.00 


4.32 




18-24 


1.0 


1.56 


.56 


3.07 


0.00 


- 3.07 



211 



28 



SOILS OF THE TRUCKEE-CAKSON lERIGATION PROJECT. 



Table V. — Effect of calcium sulphate upon nitrification in samples of soil from pint 
320, Truckee-Carson Experiment Farm, representing good soil conditions. Incubated 
15 days at 28° C. 

NO CALCIUM SULPHATE ADDED TO SAMPLES. 



No. of 
plat. 


Depth of 
soil. 


Nitrogen as nitrite (parts per 
million). 


Nitrogen as nitrate (parts per 
million). 


Original. 


final. 


Gain. 


Original. 


Final. 


Gain. 


320 


Inches. 
0-6 
6-12 
12-18 
18-24 


1.4 

1.5 

.0 

.8 


4.00 
1.20 
1.00 
1.40 


2.60 

- .30 

1.60 

.60 


3.84 
18.24 
15.90 
15.30 


80.64 

70. 80 

5.00 

0.00 


76.80 

58.56 

-10.90 

-15.30 



WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 



320 


0-6 


L4 


5.00 


3.60 


3.84 


8L60 


77.76 




6-12 


1.5 


1.68 


.13 


18.24 


76.80 


58.56 




12-18 


.0 


1.82 


1.82 


15.90 


4.56 


-11.36 




18-24 


.8 


.60 


- .20 


15.30 


.00 


-15.30 



The gain in nitrates, or the nitrifying power of these samples of 
soil, is shown in figure 18. 

These experiments on nitrification indicate that the difference in 
productiveness is not clue to a suspension of nitrification, and also 
that it is not due to the presence of sodium carbonate, as the addition 
of calcium sulphate to the samples had absoluteh' no effect: the 
treated and untreated samples could really be considered duphcates. 
It would seem also that the infertility or the lack of decay of organic 
substances is not due to lack of air. It might be argued that lab- 
oratory conditions were not such as would favor the compacting or 
cementing of the sam])les, yet it must be remembered that the corn- 
field containing plats 300, 310, and 320 was kept well cultivated and 
no crust was allowed to form during the growing season. Tables 
VI and VII show the nitrification of the different samples in Wino- 
gradsky and Omelianski's media. 

Table VI. — Nitrite formed from ammonia by samples of soil from plats 330, 340, and 
350, Truckee-Carson Experiment Farm, in medium for nitrite bacteria. Incubated 
at 28° C. 







Nitrite 


Nitrite 






Depth of 
of soil. 


formed in 


formed in 


Charac- 


No. of 
plat. 


5 days 
(parts'per 


10 days 
(parts per 


ter of 
soil. 






million). 


million). 






Inches. 








330 


0-6 


0.0 


4.8 


Poor. 




6-12 


.0 


.0 






12-18 


.0 


.0 






18-24 


.0 


.0 




340 


0-6 


9.6 


10.4 


Do. 




6-12 


12.8 


12.8 






12-18 


12.8 


12.8 






18-24 


.0 


12.2 




350 


0-6 


.0 


Trace. 


Good. 




0-12 


.0 


4.8 






12-18 


.0 


.0 






18-24 


.0 


.0 





211 



DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 



29 




Fig. 18.— Diagram showing the effect of ealcimn sulphate upon nitrification of ammonium sulphate in 
samples of soil from plat 300, Truckee-Carson Experiment Farm, representing poor soil "A "; plat 310, 
representing poor soil " B"; and plat 320, representing good soil. 

Table VII. — Nitrate formed from nitrite by samples of soil from plats 330 and 350, 
Truckee-Carson Irrigation Project, in medium for nitrate bacteria. Incubated at 28° C. 



211 







Nitrate 


Nitrate 








formed in 


formed in 


Charac- 


No. of 
plat. 


soil. 


10 days 


20 days 


ter of 


(parts per 


(parts per 


soil. 






million). 


million). 






Inches. 








330 


0-6 


24.00 


90.32 


Poor. 




6-12 


19.68 


90.32 






12-18 


12.60 


81.28 






18-24 


19. 80 


90.32 




?,m 


0-6 


12.50 


54.19 


Oood. 




(i-12 


24.00 


72. 25 






12 18 










18-24 


4.12 


90. 32 





30 



SOILS OF THE TRUCKEE-CAESON TRRIGATTON PROJECT. 



The fact that nitrification was feeble in the good soil and also in 
one of the poor soils should not be overemphasized, for soils that will 
nitrify under normal conditions frequently fail to do so in solutions. 
On the other hand, the rapidity with which the nitrate bacteria 
worked in solutions, even when they failed to do so in the soil, is 
interesting and almost without parallel. It is not surprising that a 
soil should fail to nitrify in solution, but it is remarkable that samples 
which failed to nitrify when kept warm and moist — ideal conditions 
for nitrification — should produce nitrates rapidly when inoculated 
into solutions. 

The production of ammonia from organic material by soil bacteria 
furnishes a means of measuring the power of the soil flora to break 
down nitrogenous organic substances. Thus it would seem that the 
soils of the plats in which organic matter remained indefinitely in a 



^1200 



^iiioo 

^2 1000 
IP^ 900J 



II 



DEPTH /1TWH/CH S/IMP/.ES MVEPE T/JHE/V- 






Fig. 19. — Diagram showing the ammoDification of peptone in 7 days in samples of soil from plat 350 (good 
soil) and from plats 330 and 340 (poor soil), Truckee-Carson Experiment Farm. 

state of preservation must have a very low ammonifying power. 
The medium described previously, consisting of 1.5 per cent peptone 
and inorganic salts, was inoculated with samples from plats 330, 
340, and 350, and the ammonia produced determined at 10-day and 
20-day incubation periods by distillation with magnesia.^ The 
results of this experiment are shown in figures 19 and 20. 

As the ammonification of the samples of poor soil, plats 330 and 
340, was very similar, the results are averaged and shown as a single 
curve. 

The fact that there is no increase between the 7-day and 15-day 
periods indicates that the maximum had been reached before any 

1 Dr. J. G. Lipman has recently suggested the use of dried blood as a source of 
nitrogen for work of this character. See Lipman, Jacob G., and Brown, Percy E., 
"Experiments on Ammonia and Nitrate Formation in Soils," in Centralblatt flir 
Bakteriologie, Parasitenkunde und Infektionskrankheiten, pt. 2, vol. 26, no. 20-24, 
April 9,1910, pp. 590-(i32. 
211 



DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 



31 



determinations were made. Yet these results show conclusively that 
in both good and poor soils there are large numbers of ammonifiers 
which are physiologically active if proper conditions are provided for 
them to develop. The relative differences in their ammonifying 
power and whether or not there are conditions in the soil to prevent 
their normal activities remain to be shown by further experiment. 

Denitrification is of two kinds: The reduction of nitrates to lower 
forms or transformation into organic form, and the complete breaking 
down of the nitrogenous substance with the evolution of free nitrogen 
as a gas. Either of these processes could be a source of infertility. 



^ 1 1200 
nI^IIOO 
^OOOO 



DEPT/^ y^TWA//C/^ S/JMP/.ES IA^£/?£- 7?1/<£rA/. 
J^'roG' 6'toI2" I27»I8" I8'to24" 



JS Da YSi_Goo£^ 



/SDoys- PoorSo//. 



Fig. 20.— Diagram showing the ammonification of peptone in 15 days in samples of soil from plat 350 (good 
soil) and from plats 330 and 340 (poor soil), Truckee-Carsou Experiment Farm. 

The evolution of free nitrogen was determined by measuring the 
nitrogen gas produced from i)eptone-nitrate solutions at intervals of 
7 and 15 davs. The results are rather erratic, as is shown in Table 
VIII. 



Table VIII. — Denitrification by samples of soil from plats 330, 340, and 350, Truckee- 

( 'arson Experiment Farm . 



No. of 
plat. 


Denitrification. 




Gas formed in— 




Depth of 
soil. 




Character 
of soil. 










7 days. 


15 days. 






Inches. 


Per cent. 


Per cent. 




330 


0-6 


30 


35 


Poor. 




()-12 


1 


10 






12-18 


2 


5 






18-24 


o 


5 




340 


0-6 


35 


40 


Do. 




6-12 


40 


40 






12-18 


20 


25 






18-24 


30 


40 




350 


0-6 


2 


7 


Good. 




6-12 


1 


3 






12-18 


1 


5 






18-24 


20 


20 





211 



32 



SOILS OF THE TEUCKEE-CAESON lEEIGATION PEOJECT. 



Table IX shows the difference between the good and poor soils in 
regard to total numbers and distribution of bacteria. The difference 
in the floras is more strikingly brought out when we consider the 
difference in the colonies from the difl'erent soils. The plates from 
the 6-inch and 12-inch layers of plats 300 and 310, which show low 
numbers, chiefly contained peculiar colonies surrounded by a wine- 
colored diffusible pigment. The colony itself was but slightly colored 
and, surrounded as it was by this pigment, produced a very striking 
appearance on the plates. One plate from plat 310 was apparently a 
pure culture of this organism. Such a plate obtained from soil where 
the growth or flora is almost always rich and varied is very rare, and 
is the only unusual condition thus far encountered that seems to cor- 
relate consistently with the unusual conditions of infertility. This 
peculiar colony was never seen on soils from the fertile spots, and the 
fact that it was so predominately present in the infertile soils and in 
those strata in which the peculiar black layer occurred certainly in- 
dicates that further study should be made of this point. Microscopic 
examination of the colony showed that it was a micrococcus associated 
with a mold. 

Table IX. — Total number of bacteria present in 1-gram samples of soil from plats 
300, .310, S:iO, 330, 340, and 350, Truckee- Carson Experiment Farm. 



No. of 
plat. 


Depth of 
soil. 


Number of 
bacteria 
per gram. 


Character 
of soil. 




Inches. 






300 


0-G 


458,400 


Poor. 




6-12 


45,000 






12-18 


48,900 






18-24 


178,500 




310 


0-G 


1,930,500 


Do. 




(1-12 


729,000 






12-18 


15,900 






18-24 


409,500 




320 


0-6 


507,000 


Ctood. 




6-12 


351,000 






12-18 


419,000 






18-24 


429, (.MIO 




330 


0-6 


1,3.'?5,000 


Poor. 




6-12 


915,000 






12-18 


S40, 000 






18-24 


1,197,000 




3-10 


0-6 


4,200,000 


Do. 




6-12 


525,000 






12-18 


4,620,000 






18-24 


.3,780,000 




350 


0-6 
6-12 


672,000 


(iood. 




12-18 


636,006" 






18-24 


210,000 





CONCLUSIONS. 



(1) Nitrifying, denitrifying, and ammonifying bacteria are well 
distributed and universally present in the soils of the Truckee-Carson 
Irrigation Project and become physiologically active if favorable con- 
ditions are provided for their development. 



211 



CONCLUSIONS. 33 

(2) The lack of proper decay and huinificatioii oi" organic matter in 
many of the unproductive soils is due either to unfavorable bacterial 
conditions brought about by certain i)hysical and chemical conditions 
or to an unusual bacterial flora. 

(3) The nitrifying bacteria in the soils of Fallon, Nev., are active 
at greater depths than in eastern soils and also seem to be unusually 
virile in solutions, although the data on these points are not con- 
clusive. 

(4) In general, the conditions at Fallon, as in any arid region, favor 
nitrification, which frequently becomes intense; the conditions rarely 
favor denitrification. Lack of nitrification, therefore, will not be a 
Hmiting factor in crop production, nor is there evidence of overnitrifi- 
cation or injury from excessive quantities of nitrate. Humification 
studies are probably of paramount importance. 

211 



INDEX 



Pagp. 

Apar, beef, medium for development of bacteria 9, 24 

Alkali, black. See Sodium carbonate. 

relation of chlorids and sulphates to nitrifying power 21-22 

Annnonification, definition of term , 7 

measurement of power of soil flora at Fallon, Nev 30, 31 

methods of determination in soil studies at Fallon, Nev 9, 30 

Ammonium sulphate, use in soil studies at Fallon, Nev 10, 12-22, 27, 29 

Analysis, chemical, methods employed in soil studies at Fallon, Nev 10-11, 

26-27, 30, 31 

Bacteria, colonies peculiar to certain soils at Fallon, Nev 32 

counts, methods used in soil studies at Fallon, Nev 9, 10, 26-27 

nitrifying, comparative action in soil and in solution, at Fallon, Nev. 30 
number and distribution, relation to character of soil, at Fallon, 

Nev : 24-25, 32 

Black alkali. See Sodium carbonate. 

Brown, P. E., and Lipman, J. G., on methods and results of soil studies 9, 30 

Calcium sulphate, effect upon soil samples at Fallon, Nev 26, 27-28, 29 

Chemical anaylsis. See Analysis, chemical. 

Chester, F. D., on the bacteriological analysis of soils 24 

Clay, colloidal, affected by calcium sulphate and gypsum at P'allon, Nev 26 

occurrence in soil samples at Fallon, Nev 10 

Conclusions of bulletin 32-33 

Decomposition, organic, product peculiar to poor soil at Fallon, Nev 26 

Denitrification, definition of term 7, 31 

methods of study employed at Fallon, Nev 11, 22-24, 31 

Dipotassium phosphate, use in peptone solutions at Fallon, Nev ^ 9 

Dunham's peptone solution. See Peptone, Dunham's solution. 

Extract, soil, method of preparation 10 

Failyer, G. H., and Schreiner, Oswald, on analyses of soils 11 

Fallon, Nev., locality of investigations in soil bacteriology. . . 7, 8, 11, 18, 20, 24, 25, 33 

Filtration of soil extracts, Fallon, Nev - 10 

Gypsum, effect upon colloidal clays, at Fallon, Nev 26 

Humification, importance of investigations at Fallon, Nev 33 

Introduction to bulletin 7-8 

Investigations, bacteriological, methods employed at Fallon, Nev 8-11, 

22, 26-27, 30, 31 
Jensen, C. A., determination of chlorids and sulphates in soil at Fallon, Nev. . . 11, 16 

Lipman, J. G., and Brown, P. E., on methods and results of soil studies 9, 30 

\'oorheea, E. B., on investigations in soil bacteriology 24 

on bacteriological investigations 9 

use of dried blood as a source of nitrogen 30 

Lohnis, F., on bacteriological investigations 9, 24 

Magnesium sulphate, use in peptone solutions at Fallon, Nev 9 

Methods of bacteriological investigation. See Investigations. 

Micro-organisms, relation to soil study at Fallon, Nev , 7, 8-9 

211 35 



36 SOILS OF THE TRUCKEE-CAKSON TliRIGATION PROJECT. 

I'age. 

Nitrate formed from nitrite, at Fallon, Nev 29 

Nitrification, definition and method of study, etc., at Fallon, Nev 7, 10-11 

of soil samples in solution at Fallon, Nev 12-25, 27-30 

Nitrite formed from ammonia, at Fallon, Nev ., 28 

Nitrogen, free, relation to presence of bacteria at Fallon, Nev 22, 31 

nitric, quantity originally present, in soil samples at Fallon, Nev. . 8. 12-20 

symbiotic and nonsymbiotic fixation, definition 7 

determination, at Fallon, Nev. 11 

Omelianski and Winogradsky, formula for fluid culture medium 19, 27, 28 

Peptone, ammonification in soil samples at Fallon, Nev 30, 31 

Dunham's solution, use in denitrification studies at Fallon, Nev 11, 22 

solutions, composition, used at Fallon, Nev 9 

Potassium chromate, use in determining chlorids at Fallon, Nev 11 

nitrate, ingredient of peptone solution used at Fallon, Nev 11 

Remy, Theodor, on bacteriological investigations 9 

Rogers, S. J., and Scofield, C. S., on description of Truckee-Carson Experi- 
ment Farm 8 

Schreiner, Oswald, and Failyer, G. H., on analyses of soils 11 

Scofield, C. S., on description of Truckee-Carson Experiment Farm 8 

Silver nitrate, use in determination of chlorids at Fallon, Nev 11 

sulphate, use for removal of chlorids at F'allon, Nev 11 

Sodium carbonate, presence in soils at Fallon, Nev 26, 28 

chlorid, use in peptone solutions at Fallon, Kev 9 

Soils, eastern and western, comparison of properties 12, 25, 33 

methods of treatment of samples at Fallon, Nev 8-11, 22, 26-27, 30, 31 

nitrification at different depths at Fallon, Nev 7, 12-20 

outline of plan of investigations at Fallon, Nev 7-8 

typical, detailed study at Fallon, Nev 25-32 

Sulphate of ammonia. Sre Ammonium sulphate. 

Syme, W. A., on method of estimating nitrates 11 

Truckee-Carson Experiment Farm. See Fallon, Nev. 

Urea, use in removal of nitrites from nitrates at Fallon, Nev 11 

Voorhees, E. B., and Lipman, J. G., on bacteriological investigations 24 

Winogradsky and Omelianski, formula for fluid culture medium 19, 27, 28 

211 

(J 



